The design and implementation of circularly polarized substrate integrated waveguide (SIW) antenna in X Band is presented in this paper. The substrate integrated waveguides represents the family of substrate integrated circuits which is planar in nature and used for the transmission of electromagnetic energy. In this paper the design techniques for substrate integrated waveguide using slots with the integration of microstrip are presented, which emphasis the broad perspective of the substrate integrated waveguide in circular polarization. The design has simulated in HFSS Software. From the simulation results, it is observed that gain has increased in SIW structure with slots for circular polarization as compared to SIW structure without slots. © 2016 IEEE.